Blood transfusion

Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood. Early transfusions used whole blood, but modern medical practice commonly uses only components of the blood, such as red blood cells, white blood cells, plasma, clotting factors, and platelets.
Units of packed red blood cells are typically only recommended when a person's hemoglobin levels fall below 8g/dL.[1] One may consider transfusion for people with symptoms of cardiovascular disease such as chest pain or shortness of breath.[1] Globally around 85 million units of red blood cells are transfused in a given year.[1] In cases where patients have low levels of haemoglobin but are cardiovascularly stable, parenteral iron is increasingly a preferred option based on both efficacy and safety.[2] Other blood fractions are given where appropriate, such as clotting deficiencies.
Donated blood is usually subjected to processing after it is collected, to make it suitable for use in specific patient populations. Collected blood is then separated into blood components by centrifugation: red blood cells, plasma, platelets, albumin protein, clotting factor concentrates, cryoprecipitate, fibrinogen concentrate, and immunoglobulins (antibodies). Red cells, plasma and platelets can also be donated individually via a more complex process called apheresis.
All donated blood is tested for infections. The current protocol tests donated blood fo

HIV-1, HIV-2, HTLV-1, HTLV-2, Hepatitis B, Hepatitis C, Syphilis (T pallidum), Chagas disease (T cruzi), and West Nile Virus. In addition, platelet products are also tested for bacterial infections due to its higher inclination for contamination due to storage at room temperature. Presence of Cytomegalovirus (CMV) is also tested because of risk to certain immunocompromised recipients if given, such as those with organ transplant or HIV. However, not all blood is tested for CMV because only a certain amount of CMV-negative blood needs to be available to supply patient needs. Other than positivity for CMV, any products tested positive for infections are not used.
All donated blood is also tested for ABO and Rh groups, along with the presence of any red blood cell antibodies.
Leukoreduction is the removal of white blood cells by filtration. Leukoreduced blood products are less likely to cause HLA alloimmunization (development of antibodies against specific blood types), febrile non-hemolytic transfusion reaction, cytomegalovirus infection, and platelet-transfusion refractoriness.
Pathogen Reduction treatment that involves, for example, the addition of riboflavin with subsequent exposure to UV light has been shown to be effective in inactivating pathogens (viruses, bacteria, parasites and white blood cells) in blood products.[3][4][5] By inactivating white blood cells in donated blood products, riboflavin and UV light treatment can also replace gamma-irradiation as a method to prevent graft-versus-host disease (TA-GvHD).

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